(91 days)
The KneeAlign® system is a computer-controlled system intended to assist the surgeon in determining reference alignment axes in relation to anatomical structures during stereotactic surgical procedures. The KneeAlign system facilitates the accurate positioning of implants and instrumentation, relative to these alignment axes.
Orthopedic surgical procedures include but are not limited to:
- · Total Knee Arthroplasty
- · Unicompartmental Knee Arthroplasty Tibial Transverse Resection
The KneeAlign® 2 System is a non-invasive computer assisted surgical navigation system for use in knee arthroplasty procedures. The KneeAlign® 2 System is configured to detect, measure, and display angular and positional measurement changes in a triaxial format.
The KneeAlign® 2 System utilizes a palm-sized computer module and reference sensor to generate positional information in orthopedic procedures providing a sequence of steps for registration of anatomical landmarks, calculation of mechanical axes, and positioning of instruments relative to the mechanical axes.
In total knee arthroplasty procedures, the device assists the surgeon in:
- . Establishing the mechanical axis of the femur, determining the varus/valgus angle and the flexion/extension angle of the cutting block relative to the femur.
- Establishing the mechanical axis of the tibia, determining the varus/valgus . angle and the posterior slope angle of the cutting block relative to the tibia.
In unicompartmental knee arthroplasty procedures, the device assists the surgeon in:
- Establishing the mechanical axis of the tibia, determining the varus/valgus . angle and the posterior slope angle of the cutting block relative to the tibia, for the transverse resection.
The KneeAlign® 2 System comprises a single use computer module and reusable instrumentation.
Acceptance Criteria and Study for KneeAlign 2 System
This device, the KneeAlign 2 System, is a computer-assisted surgical navigation system. Based on the provided FDA 510(k) summary, the substantial equivalence to predicate devices (KneeAlign 2 System K103829 and OrthAlign Plus System K153237) is demonstrated through technological comparison and performance testing. The key addition to the subject device is the ability to navigate tibial transverse resections in unicompartmental knee arthroplasty.
1. Table of Acceptance Criteria and Reported Device Performance
The FDA summary does not explicitly list quantitative "acceptance criteria" for accuracy performance in a tabular format with corresponding "reported device performance" values. Instead, it states that "System accuracy testing: bench testing with mechanical fixtures and foam models to verify navigated resection plane angular and depth accuracy" was performed.
For the purpose of this request, we can infer the acceptance criteria for the added functionality (tibial transverse resection in unicompartmental knee arthroplasty) by the assertion that the device is "as safe and effective as the predicate devices." The predicates were already cleared for their accuracy. Since the only performance data mentioned directly relates to this specific functionality, the "acceptance criteria" here is met by demonstrating the system's ability to accurately navigate these resections.
| Acceptance Criteria (Inferred) | Reported Device Performance |
|---|---|
| Navigated resection plane angular accuracy for tibial transverse resections in unicompartmental knee arthroplasty sufficient for intended use | "System accuracy testing: bench testing with mechanical fixtures and foam models to verify navigated resection plane angular and depth accuracy." The 510(k) states: "This testing regime demonstrates that the subject device is as safe and effective as the predicate devices. This testing regime demonstrates that the subject device is substantially equivalent to the legally marketed predicate devices, for its intended use in the accurate navigation of tibial resection planes in unicompartmental knee arthroplasty." |
| Navigated resection plane depth accuracy for tibial transverse resections in unicompartmental knee arthroplasty sufficient for intended use | (Same as above) |
| System hardware meets mechanical requirements | "System hardware verification/validation testing to ensure the instruments meet their mechanical requirements." |
| Instrumentation cleaning, sterilization, and shipping validations met | "Instrumentation cleaning, sterilization and shipping validations for the specified processes." |
| Navigation device sterilization, packaging, shelf life, environmental conditions, and shipping validations met | "Navigation device sterilization, packaging, shelf life, environmental conditions and shipping validations for the specified ranges of conditions involved in each process. (Summary data for the identical predicate device is referenced.)" |
| System components biocompatibility meets ISO 10993-1 (2009) | "System components biocompatibility assessment per ISO 10993-1 (2009)." |
| Customer requirements / usability validation in cadaver with an advising surgeon meets design input requirements in a simulated use environment | "Customer requirements / usability validation in cadaver with an advising surgeon to validate the system meets design input requirements for its functions in a simulated use environment." |
2. Sample Size Used for the Test Set and Data Provenance
- Sample Size: The document mentions "bench testing with mechanical fixtures and foam models" for accuracy testing. It does not provide specific numerical sample sizes for these tests (e.g., number of resections, number of models). For the simulated use testing, it refers to a "prospective cadaver validation" but again, no specific number of cadavers is given.
- Data Provenance:
- Country of Origin: Not explicitly stated, but given the company (OrthAlign, Inc.) is based in Aliso Viejo, California, USA, and the submission is to the U.S. FDA, it is highly likely the testing was conducted in the USA.
- Retrospective or Prospective: The cadaver validation was "prospective." The bench testing with foam models would also be considered prospective as it involves specifically designed tests for the purpose of validation.
3. Number of Experts Used to Establish the Ground Truth for the Test Set and Qualifications of Those Experts
- Number of Experts: For the "Customer requirements / usability validation," it states "with an advising surgeon." This implies at least one surgeon was involved in the simulated use ground truth establishment.
- Qualifications of Experts: The qualification mentioned is "surgeon." No further details on years of experience, sub-specialty, or board certification are provided in this summary.
4. Adjudication Method for the Test Set
- The document implies that the ground truth for "customer requirements/usability" was established by a single "advising surgeon" during the cadaver validation. There is no mention of an adjudication method involving multiple experts (e.g., 2+1, 3+1). For bench testing, the "ground truth" would be the known and controlled parameters of the mechanical fixtures and foam models.
5. If a Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study Was Done, If So, What Was the Effect Size of How Much Human Readers Improve with AI vs. Without AI Assistance
- No, an MRMC comparative effectiveness study was not done. This device is a surgical navigation system, not an AI diagnostic tool primarily aimed at improving human reading proficiency for imaging. The performance testing focuses on the device's accuracy in assisting the surgeon with measurements and positioning during a procedure, not on radiologists interpreting images.
6. If a Standalone (i.e., Algorithm Only Without Human-in-the-Loop Performance) Was Done
- Yes, in essence, standalone performance (in a controlled environment) was done for accuracy. The "System accuracy testing: bench testing with mechanical fixtures and foam models to verify navigated resection plane angular and depth accuracy" evaluates the device's algorithmic and sensor performance independent of a live surgical scenario, under controlled conditions where the "ground truth" (correct angles and depths) is preset. The "human-in-the-loop" (a surgeon) is then involved in the usability and simulated use validation.
7. The Type of Ground Truth Used
- Bench Testing: The ground truth for angular and depth accuracy was established through the known parameters of "mechanical fixtures and foam models." This represents a controlled, engineered ground truth.
- Simulated Use (Cadaver Validation): The ground truth was established by the "advising surgeon" determining if the system "meets design input requirements for its functions." This is a clinical expert consensus/assessment ground truth within a simulated environment.
8. The Sample Size for the Training Set
- This document is a 510(k) summary for a surgical navigation system, not an AI/machine learning device that typically requires a large 'training set'. The principles of operation are based on inertial sensors and calculation of spatial coordinates (not deep learning). Therefore, the concept of a "training set" for an algorithm to learn from data (as in AI) does not apply in the context of this device's validation as described. The device utilizes algorithms based on established physics and geometry.
9. How the Ground Truth for the Training Set Was Established
- As explained in point 8, the concept of a "training set" and its associated ground truth establishment is not applicable to the validation of this device as presented in the 510(k) summary. The algorithms are based on known mathematical principles for converting sensor outputs into spatial coordinates. Their accuracy is verified through empirical testing against known standards (bench testing), not "trained" on a dataset.
§ 882.4560 Stereotaxic instrument.
(a)
Identification. A stereotaxic instrument is a device consisting of a rigid frame with a calibrated guide mechanism for precisely positioning probes or other devices within a patient's brain, spinal cord, or other part of the nervous system.(b)
Classification. Class II (performance standards).